Salt is detrimental to the health of a lawn, often causing brown, dead patches along walkways and driveways. The compounds in common salts compromise the grass’s ability to thrive and fundamentally alter the soil structure. Understanding how salt affects turfgrass and soil is the first step in protecting and restoring your lawn.
How Salt Damages Grass and Soil
The primary mechanism by which salt harms grass is severe dehydration, known as physiological drought. When salt ion concentration is higher in the soil water than inside the grass roots, osmosis reverses. Water is drawn out of the roots and back into the soil, drying out the plant even if the ground is moist.
This lack of available water causes the browning and wilting of salt-damaged turf, preventing basic functions like photosynthesis. Sodium and chloride ions are directly toxic to grass cells, accumulating in tissues and interfering with nutrient uptake. Excess sodium ions compete with beneficial nutrients like potassium and magnesium, leading to imbalances that stunt growth and cause yellowing.
High sodium concentrations severely compromise the physical quality of the soil. Sodium ions cause fine clay particles to disperse, destroying the natural soil aggregates that create pore spaces. This dispersion leads to compaction, reducing aeration and slowing water infiltration. Compacted, poorly draining soil traps the salts, intensifying damage and creating a long-term hazard for future growth.
Everyday Sources of Salt Exposure
The most recognized source of salt exposure is the application of de-icing products during winter months. Common rock salt (sodium chloride) dissolves and runs off sidewalks and driveways onto adjacent turf. Other de-icers, such as calcium, magnesium, or potassium chloride, can cause similar soil damage.
Salt exposure is not limited to winter; everyday lawn care practices also contribute to salinity problems. Over-fertilization, especially with potassium chloride products, introduces high levels of chloride ions. Irrigation water naturally high in dissolved salts, such as from certain groundwater sources, leads to gradual salt buildup as the water evaporates.
In coastal regions, wind-carried salt spray deposited onto the grass or soil is a continuous source of high salinity. Even inland, irrigation with water processed by a household water softener introduces sodium ions that accumulate in the soil over time.
Repairing Salt Damaged Lawns and Soil
Repairing salt damage starts by addressing the high salt concentration in the root zone. The most effective initial step is leaching, which involves applying large volumes of clean water to the affected areas. This deep watering dissolves soluble salts and pushes them downward, below the level where grass roots can absorb them.
Ensure the damaged area has adequate drainage, as waterlogging compounds the problem by suffocating the roots. After flushing, apply a soil amendment like gypsum (calcium sulfate) to correct sodium-related soil structure issues. The calcium ions in the gypsum displace the harmful sodium ions attached to the soil particles.
The freed sodium combines with the sulfate from the gypsum, forming sodium sulfate, which is highly soluble and easily flushed from the soil profile with additional watering. Apply pelletized gypsum at 20 to 40 pounds per 100 square feet, watering it in deeply immediately after application. Once the salts are flushed, rake out the dead grass and overseed the bare patches.
Protecting Grass from Future Salt Exposure
Proactive measures are the most effective way to limit the recurrence of salt damage. One simple method involves creating physical barriers in high-risk areas, such as along driveways or roads where de-icing salts are used. Installing short fences, plastic edging, or burlap helps block salt-laden slush and spray from reaching the lawn.
Switching to less harmful de-icing materials is a highly effective strategy near walkways. Alternatives like calcium magnesium acetate (CMA) are safer for plants and soil than traditional sodium chloride rock salt. Magnesium chloride is another less damaging option, or you can use abrasive materials like coarse sand or kitty litter for traction instead of a melting agent.
For lawns consistently exposed to salty conditions, selecting a naturally salt-tolerant grass species provides long-term protection. These varieties are better equipped to handle higher soil salinity than sensitive species like Kentucky bluegrass:
- Tall fescue
- Perennial ryegrass
- Bermuda grass
- Zoysia grass
Additionally, ensuring hard surfaces slope slightly away from the lawn helps redirect salty runoff toward proper drainage.